Channel culture devices which provide multiple plant growth channels are of definite length but shallow depth and narrow individual width have the most potential for increasing the world's food supply. These channels provide maximum plant production for a given supply of fertile soil, water, fertilizer and insecticide. Some or all of which are scarce and at an extreme premium in many parts of the world. The growth channels have a limited volumetric area that can be made just sufficient for the full growth development with any specified plant so that optimum availability of nutrients and water to the plant is obtained. Further the isolation of the channels prevents the leaching and escape of the available supply of nutrients and water into the underlying soil. Isolation also simplifies the problems of cultivation and the control of pests, disease, and weeds.
Various design proposals have been made which some are disclosed and claimed in my copending U.S. Pat. application Ser. No. 512,518 filed Oct. 7, 1974 for CHANNEL CULTURE DEVICE and in my recently issued U.S. Pats., Nos. 3,987,587 and 4,014,135 both for MODULAR CHANNEL CULTURE DEVICE.
Many modular configurations have thus been suggested. it has been found in practice that most modular channel configurations incur two major drawbacks. Typically they are of a predetermined size and to achieve flexibility of sizes within a particular total assembly have proved cumbersome and expensive. Modular plant devices which have the ability to be extended both in length and breadth through some type of interfitting or interlocking connections and have not exhibited the necessary structural flexibility to form readily modules of different sizes.
More importantly most configurations have resulted in an environment for containing and supporting the plant and plant support systems which allow a modest amount of flow of water downwardly from the top surface and along the walls. Lateral flow of air and water into and from the plant support system in a channel as a practical matter did not occur. These concepts were then felt not to be important in that the total amount of nutrients required to maximize plant growth could be carefully controlled because there would generally be no leaching from the culture device. It has been found that this nonleaching concept although theoretically sound had attendant problems which in many instances outweighed the advantages. For example, when used in small scale, i.e., home, small garden areas, etc., there is a tendency by the user to overwater or overfeed. The accumulated water could not drain properly being sealed on three sides, and this condition deleteriously affected plant growth. In large scale operations unexpected rainfall results in the same problem.
My recent work in this area has established that the concept of increased aeration of the plant support system while providing some structure to minimize complete leaching did not overcome the aforementioned problems. These problems were substantially overcome in my pending U.S. application, Ser. No. 763,821 for MODULAR PLANT DEVICE.
The invention of my parent application comprises at least one growing channel such as elongated troughs which have a floor and two walls characterized by being fluid permeable, that is air and water may flow therethrough. The growing channel is flanked by two service channels which function in combination with the growing channel to allow fluids such as air and water to communicate laterally with the plant support system in the growing channel.
Therefore, in my previous work I have stressed the flexibility inherent in the system in which the plants environments may be manipulated with ease and the use of water, fertilizer, etc. held at minimum level.
Field tests of the above devices although excellent for growing purposes resulted in additional improvements which developed an improved service channel, called in this application an interior channel, and also an improved exterior channel which eliminates buckling of exterior walls which sometimes occur when an assembly was completely wetted.